High amp alternator issues-what to do about the fusible links. - JeepForum.com
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Unread 07-01-2011, 11:53 AM   #1
grimjeeperyj14
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1990 YJ Wrangler 
 
Join Date: Sep 2009
Location: Northampton, PA
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High amp alternator issues-what to do about the fusible links.

I have a 1995 pontiac 140 amp alternator that im putting in my 1990 wrangler. i already swaped the serpentine pulley to my vbelt pulley and modded the bracket. Now my issue is how to you run the high amps without burning out the stock fusible links? Do I link a fuse or relay into it somehow?

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Unread 07-01-2011, 01:20 PM   #2
Noltz
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The simplest solution is to get a 150A fuse and holder from a car stereo shop and replace the fusible link with that. Last one I bought in a waterproof container with a 100A fuse was $20.

Something to consider is that most cars do NOT fuse between the alternator and the battery. It's a direct line, sometimes daisy-chain through the starter terminal. I would do it this way and eliminate a possible failure point.

And if ya wanna get fancy;
http://www.amazon.com/Bussmann-Hi-Amp-Circuit-Breaker-Amps/dp/B0024JOKM4 $25.
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Unread 07-01-2011, 03:37 PM   #3
dancytron
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Is what you have electrically now totally stock other than the alternator?

If so, the only fusible link you need to worry about is the one that leads from the starter relay to the alternator batt + terminal. Everything else isn't going to draw any more power than it already was with the old alternator.

You can bypass it with a cable (4 gauge or so) directly from the battery positive terminal to the alternator batt + terminal. Fuse it as close to the battery as you can with a 150 amp fuse. You can unhook the old one or follow it through the loom and remove it if you want to.

Then, when you add accessories, just do it in a way that doesn't add any power draw through the old system.

Fuses and holders here are a lot cheaper than the ones at the fancy stereo store.

The poster above is right, a lot of times people don't fuse them, but as cheap as the fuses are, I don't see any reason not to.

http://www.donrowe.com/accessories/fuse_anl.html
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Unread 07-01-2011, 03:51 PM   #4
5-90
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Quote:
Originally Posted by Noltz View Post
The simplest solution is to get a 150A fuse and holder from a car stereo shop and replace the fusible link with that. Last one I bought in a waterproof container with a 100A fuse was $20.

Something to consider is that most cars do NOT fuse between the alternator and the battery. It's a direct line, sometimes daisy-chain through the starter terminal. I would do it this way and eliminate a possible failure point.

And if ya wanna get fancy;
Bussmann High-amp circuit breaker $25.
Not so - every vehicle I've worked on (which goes back to about 1955 production) has had some variety of circuit protection in that circuit. A fusible link is common in older vehicles, but it could also be a gang of MAXI fuses, a MEGA fuse (later Fords,) or any of three styles of PAL fuse (Japanese imports.) I don't recall what's used on European cars - I try to avoid working on them.

If you can't see a fuse, it's probably a fusible link - follow that lead up from the back of the alternator, and you'll probably see the last six inches of it as visibly smaller than the rest. That's the fusible link.

I typically upgrade that circuit using an ANL fuse - they're probably easiest to find for anything over 100A (they're used extensively in autosound.) Information on my site, link in sig.
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Unread 07-01-2011, 04:06 PM   #5
Alfons
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1992 YJ Wrangler 
 
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The higher output alternator itself doesn't need a different fuseable link. If you increase the amperage draw on a particular circuit, then you need to change the wiring size to manage the amperage you're going to use and to fuse it appropriately. The high amp alternator doesn't force all that amperage into circulation, but it's there is you need it. My recommendation is to plan out how you're going to use the amperage and then to get another power distribution center and add that to the "input side". Have the new power distribution center capable of handling all the amperage, using large fuses or breakers at the main input end and add the original jeep power distribution center to the new one, but add it as a circuit and fuse it to the value of the fuseable link - this will allow you to fully utilize the output of the alternator for whatever you decide on in the future and also to protect the original circuits with almost no changes. You can add supplementary fuse panels to the larger capacity distribution center if you have a bunch of other stuff to add & you can wire up a separate harness that would go from that panel to whatever new stuff you're installing.
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Unread 07-01-2011, 04:07 PM   #6
dancytron
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5-90 and OP,

On a 1990 Wrangler with a 4.2 (what OP has), an 8 gauge wire runs to the starter relay post. On that same post is 4 or 5 (don't remember exactly) fusible links that feed the whole wiring harness. The one that goes to the alternator is a fusible link and then a 10 gauge wire.

5-90, you are much more of an expert than me so correct me if I am wrong, but the only one he needs to upgrade is the one that goes to the alternator, which he can bypass as I described.

edit: and then run anything new through an auxiliary fuse box so you don't add any draw to the original fusible links.
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